feat: name live feed routes and sources for what they serve

The flight, military and vessel feeds were named after the providers the
bundled server uses (/api/opensky, /api/adsblol/mil, /api/ais-live and
their track routes; createOpenSkySource, createAdsbLolSource,
createAisStreamSource). Any server should be able to answer a feed from
its own provider, so the feeds are now:

  /api/flights   /api/flights/track?icao24=
  /api/military  /api/military/track?hex=
  /api/vessels   /api/vessels/track?mmsi=

with createFlightSource, createMilitarySource and createVesselSource. The
old routes are removed. Each server names its provider in X-Feed-Source
(the bundled server sends OpenSky Network, adsb.lol and AISStream, so its
attribution is unchanged) and the military feed's cache state and age in
X-Feed-Cache and X-Feed-Age-Ms. Sources report the provider the server
names and fall back to the feed's name.

scripts/qa-floor-hold.mjs

@@ -89,7 +89,7 @@ await page.evaluateOnNewDocument((site, icao) => {
       window.__TERRAIN.ok += 1;
       return realFetch(input, init);
     }
-    if (app && url.pathname === '/api/opensky') {
+    if (app && url.pathname === '/api/flights') {
       const c = window.__CONTACT;
       const t = Math.floor(Date.now() / 1000);
       // baro_altitude (7) and geo_altitude (13) both null, on_ground true.
@@ -99,7 +99,7 @@ await page.evaluateOnNewDocument((site, icao) => {
           null, true, 1.5, 90, 0, null, null, null, false, 0]],
       }));
     }
-    if (app && url.pathname === '/api/opensky-track') return Promise.resolve(json({ path: [] }));
+    if (app && url.pathname === '/api/flights/track') return Promise.resolve(json({ path: [] }));
     if (app && /^\/api\/adsbdb\//.test(url.pathname)) return Promise.resolve(json({}));
     return realFetch(input, init);
   };